After a number of years of enterprise Local Area Network (LAN) evolution, a stable architecture has been arrived at that has become ubiquitous worldwide (with over 3 billion LAN user connections in 2010 projected to grow to over 20 billion by 2020). This architecture is essentially a star topology where every user computer or other network connected device is connected to a Layer 2 switch via a direct cable. The upstream ports on the switch are connected to servers, routers or other switches to complete the network.
In the vast majority of these networks, the cables connecting these user devices to the switch is CAT 5 cable, and the connection protocol is 100 Megabit Ethernet with a maximum span length of 100 m. Power can be provided in addition to the communications via the Power over Ethernet (PoE) standard to a maximum of 30 W. In facilities where there are longer distances, the “edge” switches are placed closer to the user, and networks of switches are created to create an additional network upstream of the edge switch. Network performance is characterized by not only the speed of the data links, but also the delay, or latency, for the signals to go over the cable and through the layers of switching devices. The more switches in line between a user and another user or a server or the Internet the worse the overall network performance.
The exponential growth in both the number of network connected devices and in the consumption of multimedia-related content places increasing demands for higher bandwidth on the enterprise networks that support them. However, conventional network configurations, which are often based on home-run connections from an edge switch to a client device based on long runs of Category 5 (CAT 5) cables, are unable to accommodate the bandwidth growth necessary to meet these increasing demands due to the limitations in bandwidth over long distances for CAT 5 cables.
In particular, Layer 2 switches comprise Input/Output interfaces and a switch fabric. Layer 2 switching is very fast and has low latency. The inclusion of other network features has led to the deployment of edge switches that have Layer 3 and 4 functionality as well. The addition of mobile users and the need for reconfigurability has led to the LAN network being overlaid with wireless multi-access networks such as defined by the 802.11 WiFi standard. Early Layer 2 star networks were used primarily for accessing local network resources such as servers, storage, or printers or wide area network or basic WAN internet functions such as email and web page viewing. New applications, such as video viewing, rich media web or social networks and video conferencing, have increased the need for higher bandwidth, lower latency (delay) LAN networks. Unfortunately, current networks are limited to 100 Mbs by the use of the CAT 5 Cable and the lengths of the cable runs. One way that networks are being upgraded to achieve 1000 Mbs or 1 Gbs speed is by moving the edge switch closer to groups of users, often below 20 m where 1000 BaseT (Gigabit Ethernet) will run reliably on CAT 5 cable. While solving the cable speed problem, this approach introduces additional problems by both increasing network complexity and network latency.
Network administrators try to achieve better performance by upgrading the cable in the user home run links to higher grades of cable like Category 6 (CAT 6) or Category 7 (CAT 7) cable. These types of solutions are in themselves only temporary as bandwidth increases above 1G to 10G will only bring back the same problem. These conventional upgrade approaches, involving replacement of existing CAT 5 cables with CAT 6 or CAT 7 cables or adding remote network switches deep in the network within GbE reach of a CAT 5 cable, are not ideal, as they add significant amounts of network latency and complexity while only offering modest improvements to overall network performance. Further, these higher-category cables have significant cost premiums.
Using fiber optic links instead of CAT cables is another option in communications networks, but fiber optic technology has not gained much traction in the enterprise network context due to the high cost of conventional fiber optic transceivers, the labor costs involved in installing and terminating conventional fiber optic links, and the inability of conventional fiber optic links to interface with Power over Ethernet (PoE) connections and network components utilizing the PoE standard.